Drag reduction of asphaltenic crude oils

ABSTRACT

The process begins by obtaining a first batch of monomers selected from a group of acrylates with a molecular weight equal to or less than butyl acrylate and/or methacrylate with a molecular weight equal to or less than butyl methacrylate. A second batch of monomers is then selected from a group of acrylates with a molecular weight greater than butyl acrylate and/or methacrylate with a molecular weight greater than butyl methacrylate. A mixture is then prepared by mixing the first batch of monomers and the second batch of monomers, wherein the second batch of monomers are greater than 50% by weight of the mixture. Finally, the mixture is polymerized to produce a drag reducing polymer. The drag reducing polymer is capable of imparting drag reducing properties in liquid hydrocarbons.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application which claims thebenefit of and priority to U.S. application Ser. No. 11/615,539 filedDec. 22, 2006, entitled “Drag Reduction of Asphaltenic Crude Oils,” andU.S. application Ser. No. 13/208,951, filed Aug. 12, 2011, entitled“Monomer Selection to Prepare Ultra High Molecular Weight Drag ReducerPolymer”, which are hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to high molecular weight dragreducers for use in crude oils.

BACKGROUND

When fluids are transported by a pipeline, there is typically a drop influid pressure due to friction between the wall of the pipeline and thefluid. Due to this pressure drop, for a given pipeline, fluid must betransported with sufficient pressure to achieve the desired throughput.When higher flow rates are desired through the pipeline, more pressuremust be applied due to the fact that, as flow rates are increased, thedifference in pressure caused by the pressure drop also increases.However, design limitations on pipelines limit the amount of pressurethat can be employed. The problems associated with pressure drop aremost acute when fluids are transported over long distances. Suchpressure drops can result in inefficiencies that increase equipment andoperation costs.

To alleviate the problems associated with pressure drop, many in theindustry utilize drag reducing additives in the flowing fluid. When theflow of fluid in a pipeline is turbulent, high molecular weightpolymeric drag reducers can be employed to enhance the flow. A dragreducer is a composition capable of substantially reducing friction lossassociated with the turbulent flow of a fluid through a pipeline. Therole of these additives is to suppress the growth of turbulent eddies,which results in higher flow rate at a constant pumping pressure.Ultra-high molecular weight polymers are known to function well as dragreducers, particularly in hydrocarbon liquids. In general, dragreduction depends in part upon the molecular weight of the polymeradditive and its ability to dissolve in the hydrocarbon under turbulentflow. Effective drag reducing polymers typically have molecular weightsin excess of five million.

Conventional polymeric drag reducers, however, typically do not performwell in crude oils having a low API gravity and/or a high asphaltenecontent. Accordingly, there is a need for improved drag reducing agentscapable of reducing the pressure drop associated with the turbulent flowof low API gravity and/or high-asphaltene crude oils through pipelines.

However not every monomer can be polymerized as drag reducing polymer.Even when monomers are selected that are known to have the ability to bepolymerized as drag reducing polymers not all can be shown to impartdrag reducing properties. There exists a need to find which polymers canimpart drag reducing properties.

SUMMARY OF THE INVENTION

The process begins by obtaining a first batch of monomers selected froma group of acrylates with a molecular weight equal to or less than butylacrylate and/or methacrylate with a molecular weight equal to or lessthan butyl methacrylate. A second batch of monomers is then selectedfrom a group of acrylates with a molecular weight greater than butylacrylate and/or methacrylate with a molecular weight greater than butylmethacrylate. A mixture is then prepared by mixing the first batch ofmonomers and the second batch of monomers, wherein the second batch ofmonomers are greater than 50%/n by weight of the mixture. Finally, themixture is polymerized to produce a drag reducing polymer. The dragreducing polymer is capable of imparting drag reducing properties inliquid hydrocarbons.

In yet another embodiment a process is taught of obtaining a first batchof monomers selected from a group of acrylates with side alkyl chainshaving four or less carbons and/or methacrylates with side alkyl chainshaving four or less. A second batch of monomers are selected from agroup of acrylates with side alkyl chains having greater than fourcarbons and/or methacrylates with side alkyl chains greater than fourcarbons. A mixture is then prepared by mixing the first batch ofmonomers and the second batch of monomers, wherein the second batch ofmonomers are greater than 50% by weight of the mixture. Finally, themixture is polymerized to produce a drag reducing polymer. The dragreducing polymer is capable of imparting drag reducing properties inliquid hydrocarbons.

In another embodiment a process is taught for selecting monomers topolymerize into an ultra high molecular weight polymer. In thisembodiment a process is taught of first obtaining a first batch ofmonomers selected from a group of acrylates with side alkyl chainshaving four or less carbons and/or methacrylates with side alkyl chainshaving four or less. A second batch of monomers are selected from agroup of acrylates with side alkyl chains having greater than fourcarbons and/or methacrylates with side alkyl chains greater than fourcarbons. A mixture is then prepared by mixing the first batch ofmonomers and the second batch of monomers, wherein the second batch ofmonomers are greater than 50% by weight of the mixture. Finally, themixture is polymerized to produce a drag reducing polymer. The dragreducing polymer is capable of imparting drag reducing properties inliquid hydrocarbons.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A preferred embodiment of the present invention is described in detailbelow with reference to the attached drawing figures, wherein:

FIG. 1 is a normalized filament diameter vs. time plot depicting thenormalized capillary breakup time for untreated San Joaquin Valley HeavyCrude Oil determined in accordance with the procedure described inExample 4;

FIG. 2 is a normalized filament diameter vs. time plot depicting thenormalized capillary breakup time for San Joaquin Valley Heavy Crude Oilhaving 500 parts per million by weight (ppmw) of poly(2-ethylhexylmethacrylate) dissolved therein determined in accordance with theprocedure described in Example 4; and

FIG. 3 is a normalized filament diameter vs. time plot depicting thenormalized capillary breakup time for San Joaquin Valley Heavy Crude Oilhaving 500 ppmw of a poly(l-decene) dissolved therein determined inaccordance with the procedure described in Example 4.

FIG. 4 depicts a process of preparing an ultra high molecular weightpolymer.

FIG. 5 depicts a process of preparing an ultra high molecular weightpolymer.

DETAILED DESCRIPTION

In accordance with one embodiment of the present invention, the pressuredrop associated with flowing a liquid hydrocarbon through a conduit,such as a pipeline, can be reduced by treating the liquid hydrocarbonwith a drag reducing polymer having at least one heteroatom. In oneembodiment, the liquid hydrocarbon can be a heavy crude oil.

In one embodiment a process is taught of preparing a drag reducingpolymer to impart maximum drag reduction properties. FIG. 4 is aflowchart depicting this process. Step 201 describes the first step inthe process of obtaining a first batch of monomers selected fromacrylates and/or methacrylates. The selection to use solely acrylates,solely methacrylates or a combination of acrylates and methacrylatesdepends upon different pricing models and different applications of theultra high molecular weight polymer produced at the end. In thisembodiment the acrylates can have a molecular weight equal to or lessthan butyl acrylate. Additionally, the methacrylates can have amolecular weight equal to or less than butyl methacrylate. Examples ofacrylates or methacrylates that can be in the first batch include methylacrylate, ethyl acrylate, propyl acrylates, butyl acrylates, methylmethacrylate, ethyl methacrylate, propyl methacrylates, butylmethacrylates and combinations and isomeric forms of these acrylates andmethacrylates.

Step 202 describes the second step in the process wherein a second batchof monomers is selected from acrylates and/or methacrylates. In thisembodiment the acrylates can have a molecular weight greater than butylacrylate. Additionally, the methacrylates can have a molecular weightgreater than butyl methacrylate. Examples of acrylates or methacrylatesthat can be in the second batch include pentyl acrylate, pentylmethacrylate, isopentyl acrylate, isopentyl methacrylate, hexylacrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexylmethacrylate, heptyl acrylate, heptyl methacrylate, octyl acrylate,octyl methacrylate, isooctyl acrylate, isooctyl methacrylate, isodecylacrylate, isodecyl methacrylate, lauryl acrylate, lauryl methacrylate,2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, benzyl acrylate,benzyl methacrylate, 2-phenylethyl acrylate, 2-phenylethyl methacrylate,tridecyl acrylate, tridecyl methacrylate, isobornyl acrylate, isobornylmethacrylate, 3,55-trimethylhexyl acrylate, 3,5,5-trimethylhexylmethacrylate, 3,3,5-trimethylcyclohexyl acrylate,3,3,5-trimethylcyclohexyl methacrylate and combinations and isomericforms of these acrylates and methacrylates.

A mixture can now be prepared 204 by mixing the first batch 201 with thesecond batch 202. In this mixture different quantities of second batchby weight can be used when compared to the total mixture by weight. Inone embodiment the second batch is greater than 50% by weight of themixture, in other embodiment the second batch can be 50%, 55%, 60%, 65%,70%, 75%, 80%, 85%, 90%, 98%, 99%, or even 100% of the mixture is of thesecond batch.

Finally the mixture is polymerized to produce a drag reducing polymer206.

In yet another embodiment a process is taught of preparing a dragreducing polymer to impart maximum drag reduction properties. FIG. 5 isa flowchart depicting this process. Step 301 describes the first step inthe process of obtaining a first batch of monomers selected fromacrylates and/or methacrylates. In this embodiment the acrylates canhave a side alkyl chains having four or less carbons. Additionally themethacrylates can have side alkyl chains having four or less carbons.

Step 302 describes the second step in the process wherein a second batchof monomers is selected from acrylates and/or methacrylates. In thisembodiment the acrylates can have a side alkyl chains having greaterthan four carbons. Additionally the methacrylates can have side alkylchains having greater than four carbons. In yet another embodiment step303 can also select the acrylates and methacrylates with side alkylbranching chains versus those with side alkyl straight chains.

A mixture can now be prepared 304 by mixing the first batch 301 with thesecond batch 302. In this mixture different quantities of second batchby weight can be used when compared to the total mixture by weight. Inone embodiment the second batch is greater than 50% by weight of themixture, in other embodiment the second batch can be 50%, 55%, 60%, 65%,70%, 75%, 80%, 85%, 90%, 98%, 99%, or even 100% of the mixture is of thesecond batch.

Finally the mixture is polymerized to produce a drag reducing polymer306.

In one embodiment of the present invention, the liquid hydrocarbon cancomprise asphaltene compounds. As used herein, “asphaltenes” are definedas the fraction separated from crude oil or petroleum products uponaddition of pentane, as described below in Example 3. While difficult tocharacterize, asphaltenes are generally thought to be high molecularweight, non-crystalline, polar compounds which exist in crude oil. Inone embodiment of the present invention, the liquid hydrocarbon cancomprise asphaltene compounds in an amount of at least about 3 weightpercent, in the range of from about 4 to about 35 weight percent, or inthe range of from 5 to 25 weight percent.

In another embodiment of the present invention, the liquid hydrocarboncan comprise heteroatoms. As used herein, the term “heteroatom” isdefined as any atom that is not a carbon or hydrogen atom. Typically,heteroatoms include, but are not limited to, sulfur, nitrogen, oxygen,phosphorus, and chlorine atoms. In one embodiment, the liquidhydrocarbon can comprise sulfur in an amount of at least about 1 weightpercent, in the range of from about 1 to about 10 weight percent, in therange of from about 1.2 to about 9 weight percent, or in the range offrom 1.5 to 8 weight percent. Additionally, the liquid hydrocarbon cancomprise nitrogen in an amount of at least about 1,300 parts per millionby weight (ppmw), at least about 1,400 ppmw, or at least 1,500 ppmw.

In another embodiment of the present invention, the liquid hydrocarboncan comprise one or more metal components. In one embodiment, the liquidhydrocarbon can comprise metals in an amount of at least about 1 ppmw,in the range of from about 1 to about 2,000 ppmw, in the range of fromabout 50 to about 1.500 ppmw, or in the range of from 100 to 1,000 ppmw.Typical metals include, but are not limited to, nickel, vanadium, andiron. In one embodiment, the liquid hydrocarbon can comprise nickel inan amount of at least about 1 ppmw, in the range of from about 5 toabout 500 ppmw, or in the range of from 10 to 250 ppmw. Additionally,the liquid hydrocarbon can comprise vanadium in an amount of at leastabout 1 ppmw, in the range of from about 5 to about 500 ppmw, or in therange of from 10 to 250 ppmw. Further, the liquid hydrocarbon cancomprise iron in an amount of at least about 1 ppmw, in the range offrom about 2 to about 250 ppmw, or in the range of from 5 to 100 ppmw.

In another embodiment of the present invention, the liquid hydrocarboncan comprise a residuum. As used herein, the term “residuum” is definedas the residual material remaining in the bottom of a fractionatingtower after the distillation of crude oil as determined by ASTM testmethod D2892-05. In one embodiment, the liquid hydrocarbon can compriseat least about 10 weight percent, at least about 15 weight percent, orin the range of from 20 to 60 weight percent of a residuum having aninitial boiling point of at least about 1,050° F.

In another embodiment, the liquid hydrocarbon can comprise conradsoncarbon. As used herein, the term “conradson carbon” is defined as themeasured amount of carbon residue left after evaporation and pyrolysisof crude oil as determined by ASTM test method 0189-05. In oneembodiment, the liquid hydrocarbon can comprise conradson carbon in anamount of at least about 1 weight percent, in the range of from about 2to about 50 weight percent, in the range of from about 3.5 to 45 weightpercent, or in the range of from 5 to 40 weight percent.

In another embodiment of the present invention, the liquid hydrocarboncan have a low to intermediate API gravity. As used herein, the term“API gravity” is defined as the specific gravity scale developed by theAmerican Petroleum Institute for measuring the relative density ofvarious petroleum liquids. API gravity of a liquid hydrocarbon isdetermined according to the following formula:

API gravity=(141.5/SG at 60° F.)−131.5

where SG is the specific gravity of the liquid hydrocarbon at 60° F.Additionally, API gravity can be determined according to ASTM testmethod D1298. In one embodiment, the liquid hydrocarbon can have an APIgravity of less than about 26°, in the range of from about 5° to about25°, or in the range of from 5° to 23°.

In another embodiment of the present invention, the liquid hydrocarboncan be a component of a fluid mixture that further comprises anon-hydrocarbon fluid and/or a non-liquid phase. In one embodiment, thenon-hydrocarbon fluid can comprise water, and the non-liquid phase cancomprise natural gas. Additionally, when the liquid hydrocarbon is acomponent of a fluid mixture, the liquid hydrocarbon can account for atleast about 50 weight percent, at least about 60 weight percent, or atleast 70 weight percent of the fluid mixture.

In another embodiment of the present invention, the liquid hydrocarboncan have a solubility parameter sufficient to allow at least partialdissolution of the above mentioned drag reducing polymer in the liquidhydrocarbon. The solubility parameter (δ₂) of the liquid hydrocarbon canbe determined according to the following equation:

δ₂=[(ΔH_(v)−RT)/V]^(1/2)

where ΔH_(v) is the energy of vaporization, R is the universal gasconstant, T is the temperature in Kelvin, and V is the molar volume. δ₂is given in units of MPa^(1/2). The solubility parameter for the liquidhydrocarbon is determined in accord with the above equation and thedescription found on pages 465-467 of Strausz, O. & Lown, M., TheChemistry of Alberta Oil Sands, Bitumens and Heavy Oils (Alberta EnergyResearch Institute, 2003). In one embodiment, the liquid hydrocarbon canhave a solubility parameter of at least about 17 MPa^(1/2), or in therange of from about 17.1 to about 24 MPa^(1/2), or in the range of from17.5 to 23 MPa^(1/2).

As mentioned above, the liquid hydrocarbon can be a heavy crude oil.Suitable examples of heavy crude oils include, but are not limited to,Merey heavy crude, Petrozuata heavy crude, Corocoro heavy crude, Albianheavy crude, Bow River heavy crude, Maya heavy crude, and San JoaquinValley heavy crude. Additionally, the liquid hydrocarbon can be a blendof heavy crude oil with lighter hydrocarbons or diluents. Suitableexamples of blended crude oils include, but are not limited to, WesternCanadian Select and Marlim Blend.

As mentioned above, the liquid hydrocarbon can be treated with a dragreducing polymer. In one embodiment of the present invention, the dragreducing polymer can be in the form of a latex drag reducer comprising ahigh molecular weight polymer dispersed in an aqueous continuous phase.The latex drag reducer can be prepared via emulsion polymerization of areaction mixture comprising one or more monomers, a continuous phase, atleast one surfactant, and an initiation system. The continuous phasegenerally comprises at least one component selected from the groupconsisting of water, polar organic liquids, and mixtures thereof. Whenwater is the selected constituent of the continuous phase, the reactionmixture can also comprise a buffer. Additionally, as described in moredetail below, the continuous phase can optionally comprise a hydrateinhibitor. In another embodiment, the drag reducing polymer can be inthe form of a suspension or solution according to any method known inthe art.

In one embodiment of the present invention, the drag reducing polymercan comprise a plurality of repeating units of the residues of one ormore of the monomers selected from the group consisting of:

wherein R₁ is H or a C1-C10 alkyl radical, and R₂ is H, a C1-C30 alkylradical, a C5-C30 substituted or unsubstituted cycloalkyl radical, aC6-C20 substituted or unsubstituted aryl radical, an aryl-substitutedC1-C10 alkyl radical, a —(CH2CH2O)_(x)—R_(A) or —(CH2CH(CH3)O)_(x)—R_(A)radical wherein x is in the range of from 1 to 50 and R_(A) is H, aC1-C30 alkyl radical, or a C6-C30 alkylaryl radical;

R₃-arene-R₄  (B)

wherein arene is a phenyl, naphthyl, anthracenyl, or phenanthrenyl, R₃is CH═CH₂ or CH₃—C═CH₂, and R₄ is H, a C1-C30 alkyl radical, a C5-C30substituted or unsubstituted cycloalkyl radical, Cl, SO₃, OR_(B), orCOOR_(C), wherein R_(B) is H, a C1-C30 alkyl radical, a C5-C30substituted or unsubstituted cycloalkyl radical, a C6-C20 substituted orunsubstituted aryl radical, or an aryl-substituted C1-C10 alkyl radical,and wherein R_(C) is H, a C1-C30 alkyl radical, a C5-C30 substituted orunsubstituted cycloalkyl radical, a C6-C20 substituted or unsubstitutedaryl radical, or an aryl-substituted C1-C10 alkyl radical;

wherein R₅ is H, a C1-C30 alkyl radical, or a C6-C20 substituted orunsubstituted aryl radical;

wherein R₆ is H, a C1-C30 alkyl radical, or a C6-C20 substituted orunsubstituted aryl radical;

wherein R₇ is H or a C₁-C₁₈ alkyl radical, and R₈ is H, a C₁-C₁₈ alkylradical, or Cl;

wherein R₉ and R₁₀ are independently H, a C1-C30 alkyl radical, a C6-C20substituted or unsubstituted aryl radical, a C25-C30 substituted orunsubstituted cycloalkyl radical, or heterocyclic radicals;

wherein R₁₁ and R₁₇ are independently H, a C1-C30 alkyl radical, aC6-C20 substituted or unsubstituted aryl radical, a C5-C30 substitutedor unsubstituted cycloalkyl radical, or heterocyclic radicals;

wherein R₁₃ and R₁₄ are independently H, a C1-C30 alkyl radical, aC6-C20 substituted or unsubstituted aryl radical, a C5-C30 substitutedor unsubstituted cycloalkyl radical, or heterocyclic radicals;

wherein R₁₅ is H, a C1-C30 alkyl radical, a C6-C20 substituted orunsubstituted aryl radical, a C5-C30 substituted or unsubstitutedcycloalkyl radical, or heterocyclic radicals;

wherein R₁₆ is H, a C1-C30 alkyl radical, or a C6-C20 aryl radical;

wherein R₁₇ and R₁₈ are independently H, a C1-C30 alkyl radical, aC6-C20 substituted or unsubstituted aryl radical, a C5-C30 substitutedor unsubstituted cycloalkyl radical, or heterocyclic radicals;

wherein R₁₉ and R₂₀ are independently H, a C1-C30 alkyl radical, aC6-C20 substituted or unsubstituted aryl radical, a C5-C30 substitutedor unsubstituted cycloalkyl radical, or heterocyclic radicals.

In one embodiment of the present invention, the drag reducing polymercan comprise repeating units of the residues of C4-C20 alkyl, C6-C20substituted or unsubstituted aryl, or aryl-substituted C1-C10 alkylester derivatives of methacrylic acid or acrylic acid. In anotherembodiment, the drag reducing polymer can be a copolymer comprisingrepeating units of the residues of 2-ethylhexyl methacrylate and theresidues of at least one other monomer. In yet another embodiment, thedrag reducing polymer can be a copolymer comprising repeating units ofthe residues of 2-ethylhexyl methacrylate monomers and butyl acrylatemonomers. In still another embodiment, the drag reducing polymer can bea homopolymer comprising repeating units of the residues of 2-ethylhexylmethacrylate.

In one embodiment of the present invention, the drag reducing polymercan comprise the residues of at least one monomer having a heteroatom.As stated above, the term “heteroatom” includes any atom that is not acarbon or hydrogen atom. Specific examples of heteroatoms include, butare not limited to, oxygen, nitrogen, sulfur, phosphorous, and/orchlorine atoms. In one embodiment, the drag reducing polymer cancomprise at least about 10 percent, at least about 25 percent, or atleast 50 percent of the residues of monomers having at least oneheteroatom. Additionally, the heteroatom can have a partial charge. Asused herein, the term “partial charge” is defined as an electric charge,either positive or negative, having a value of less than 1.

The surfactant used in the above-mentioned reaction mixture can includeat least one high HLB anionic or nonionic surfactant. The term “HLBnumber” refers to the hydrophile-lipophile balance of a surfactant in anemulsion. The HLB number is determined by the methods described by W. C.Griffin in J. Soc. Cosmet. Chem., 1, 311 (1949) and J. Soc. Cosmet.Chem., 5, 249 (1954), which are incorporated herein by reference. Asused herein, the term “high HLB” shall denote an HLB number of 7 ormore. The HLB number of surfactants for use with forming the reactionmixture can be at least about 8, at least about 10, or at least 12.

Exemplary high HLB anionic surfactants include, but are not limited to,high HLB alkyl sulfates, alkyl ether sulfates, dialkyl sulfosuccinates,alkyl phosphates, alkyl aryl sulfonates, and sarcosinates. Suitableexamples of commercially available high HLB anionic surfactants include,but are not limited to, sodium lauryl sulfate (available as RHODAPON LSBfrom Rhodia Incorporated, Cranbury, N.J.), dioctyl sodium sulfosuccinate(available as AEROSOL OT from Cytec Industries, Inc., West Paterson,N.J.), 2-ethylhexyl polyphosphate sodium salt (available from JarchemIndustries Inc., Newark. N.J.), sodium dodecylbenzene sulfonate(available as NORFOX 40 from Norman, Fox & Co., Vernon, Calif.), andsodium lauroylsarcosinic (available as HAMPOSYL L-30 from HampshireChemical Corp., Lexington, Mass.).

Exemplary high HLB nonionic surfactants include, but are not limited to,high HLB sorbitan esters, PEG fatty acid esters, ethoxylated glycerineesters, ethoxylated fatty amines, ethoxylated sorbitan esters, blockethylene oxideipropylene oxide surfactants, alcohol/fatty acid esters,ethoxylated alcohols, ethoxylated fatty acids, alkoxylated castor oils,glycerine esters, linear alcohol ethoxylates, and alkyl phenolethoxylates. Suitable examples of commercially available high HLBnonionic surfactants include, but are not limited to, nonylphenoxy andoctylphenoxy poly(ethyleneoxy) ethanols (available as the IGEPAL CA andCO series, respectively from Rhodia, Cranbury. N.J.), C8 to C18ethoxylated primary alcohols (such as RHODASURF LA-9 from Rhodia Inc.,Cranbury, N.J.), C11 to C15 secondary-alcohol ethoxylates (available asthe TERGITOL 15-S series, including 15-S-7, 15-S-9, 15-S-12, from DowChemical Company, Midland, Mich.), polyoxyethylene sorbitan fatty acidesters (available as the TWEEN series of surfactants from Uniquema,Wilmington, Del.), polyethylene oxide (25) oleyl ether (available asSIPONIC Y-500-70 from Americal Alcolac Chemical Co., Baltimore. Md.),alkylaryl polyether alcohols (available as the TRITON X series,including X-100, X-165, X-305, and X-405, from Dow Chemical Company,Midland, Mich.).

In one embodiment, the initiation system for use in the above-mentionedreaction mixture can be any suitable system for generating free radicalsnecessary to facilitate emulsion polymerization. Possible initiatorsinclude, but are not limited to, persulfates (e.g., ammonium persulfate,sodium persulfate, potassium persulfate), peroxy persulfates, andperoxides (e.g., tert-butyl hydroperoxide) used alone or in combinationwith one or more reducing components and/or accelerators. Possiblereducing components include, but are not limited to, bisulfites,metabisulfites, ascorbic acid, and sodium formaldehyde sulfoxylate.Possible accelerators include, but are not limited to, any compositioncontaining a transition metal having two oxidation states such as, forexample, ferrous sulfate and ferrous ammonium sulfate. Alternatively,known thermal and radiation initiation techniques can be employed togenerate the free radicals. In another embodiment, any polymerizationand corresponding initiation or catalytic methods known by those skilledin the art may be used in the present invention. For example, whenpolymerization is performed by methods such as addition or condensationpolymerization, the polymerization can be initiated or catalyzed bymethods such as cationic, anionic, or coordination methods.

When water is used to form the above-mentioned reaction mixture, thewater can be purified water such as distilled or deionized water.However, the continuous phase of the emulsion can also comprise polarorganic liquids or aqueous solutions of polar organic liquids, such asthose listed below.

As previously noted, the reaction mixture optionally can include abuffer. The buffer can comprise any known buffer that is compatible withthe initiation system such as, for example, carbonate, phosphate, and/orborate buffers.

As previously noted, the reaction mixture optionally can include atleast one hydrate inhibitor. The hydrate inhibitor can be athermodynamic hydrate inhibitor such as, for example, an alcohol and/ora polyol. In one embodiment, the hydrate inhibitor can comprise one ormore polyhydric alcohols and/or one or more ethers of polyhydricalcohols. Suitable polyhydric alcohols include, but are not limited to,monoethylene glycol, diethylene glycol, triethylene glycol,monopropylene glycol, and/or dipropylene glycol. Suitable ethers ofpolyhydric alcohols include, but are not limited to, ethylene glycolmonomethyl ether, diethylene glycol monomethyl ether, propylene glycolmonomethyl ether, and dipropylene glycol monomethyl ether.

Generally, the hydrate inhibitor can be any composition that when mixedwith distilled water at a 1:1 weight ratio produces a hydrate inhibitedliquid mixture having a gas hydrate formation temperature at 2,000 psiathat is lower than the gas hydrate formation temperature of distilledwater at 2,000 psia by an amount in the range of from about 10 to about150° F., in the range of from about 20 to about 80° F., or in the rangeof from 30 to 60° F. For example, monoethylene glycol qualifies as ahydrate inhibitor because the gas hydrate formation temperature ofdistilled water at 2.000 psia is about 70° F., while the gas hydrateformation temperature of a 1:1 mixture of distilled water andmonoethylene glycol at 2,000 psia is about 28° F. Thus, monoethyleneglycol lowers the gas hydrate formation temperature of distilled waterat 2,000 psia by about 42° F. when added to the distilled water at a 1:1weight ratio. It should be noted that the gas hydrate formationtemperature of a particular liquid may vary depending on thecompositional make-up of the natural gas used to determine the gashydrate formation temperature. Therefore, when gas hydrate formationtemperature is used herein to define what constitutes a “hydrateinhibitor,” such gas hydrate temperature is presumed to be determinedusing a natural gas composition containing 92 mole percent methane, 5mole percent ethane, and 3 mole percent propane.

In forming the reaction mixture, the monomer, water, the at least onesurfactant, and optionally the hydrate inhibitor, can be combined undera substantially oxygen-free atmosphere that is maintained at less thanabout 1,000 ppmw oxygen or less than about 100 ppmw oxygen. Theoxygen-free atmosphere can be maintained by continuously purging thereaction vessel with an inert gas such as nitrogen and/or argon. Thetemperature of the system can be kept at a level from the freezing pointof the continuous phase up to about 60° C., in the range of from about 0to about 45° C., or in the range of from 0 to 30′C. The system pressurecan be maintained in the range of from about 5 to about 100 psia, in therange of from about 10 to about 25 psia, or about atmospheric pressure.However, higher pressures up to about 300 psia can be necessary topolymerize certain monomers, such as diolefins.

Next, a buffer can be added, if required, followed by addition of theinitiation system, either all at once or over time. The polymerizationreaction is carried out for a sufficient amount of time to achieve atleast about 90 percent conversion by weight of the monomers. Typically,this time period is in the range of from between about 1 to about 10hours, or in the range of from 3 to 5 hours. During polymerization, thereaction mixture can be continuously agitated.

The following table sets forth approximate broad and narrow ranges forthe amounts of the ingredients present in the reaction mixture.

Ingredient Broad Range Narrow Range Monomer (wt. % of reaction 10-60%30-50% mixture) Water (wt. % of reaction 20-80% 50-70% mixture)Surfactant (wt. % of 0.1-10%  0.25-6%  reaction mixture) Initiationsystem Monomer:Initiator 1 × 10³:1-5 × 10⁶:1 5 × 10³:1-2 × 10⁶:1 (molarratio) Monomer:Reducing Comp. 1 × 10³:1-5 × 10⁶:1 5 × 10³:1-2 × 10⁶:1(molar ratio) Accelerator:Initiator 0.001:1-10:1 0.005:1-1:1 (molarratio) Buffer 0 to amount necessary to reach pH of initiation (initiatordependent, typically between about 6.5-10) Optional hydrate If present,the hydrate inhibitor inhibitor can have a hydrate inhibitor-to-waterweight ratio from about 1:10 to about 10:1, about 1:5 to about 5:1, or2:3 to 3:2.

The emulsion polymerization reaction yields a latex compositioncomprising a dispersed phase of solid particles and a liquid continuousphase. The latex can be a stable colloidal dispersion comprising adispersed phase of high molecular weight polymer particles and acontinuous phase comprising water. The colloidal particles can comprisein the range of from about 10 to about 60 percent by weight of thelatex, or in the range of from 40 to 50 percent by weight of the latex.The continuous phase can comprise water, the high HLB surfactant, thehydrate inhibitor (if present), and buffer as needed. Water can bepresent in the range of from about 20 to about 80 percent by weight ofthe latex, or in the range of from about 40 to about 60 percent byweight of the latex. The high HLB surfactant can comprise in the rangeof from about 0.1 to about 10 percent by weight of the latex, or in therange of from 0.25 to 6 percent by weight of the latex. As noted in thetable above, the buffer can be present in an amount necessary to reachthe pH required for initiation of the polymerization reaction and isinitiator dependent. Typically, the pH required to initiate a reactionis in the range of from 6.5 to 10.

When a hydrate inhibitor is employed in the reaction mixture, it can bepresent in the resulting latex in an amount that yields a hydrateinhibitor-to-water weight ratio in the range of from about 1:10 to about10:1, in the range of from about 1:5 to about 5:1, or in the range offrom 2:3 to 3:2. Alternatively, all or part of the hydrate inhibitor canbe added to the latex after polymerization to provide the desired amountof hydrate inhibitor in the continuous phase of the latex.

In one embodiment of the present invention, the drag reducing polymer ofthe dispersed phase of the latex can have a weight average molecularweight (M_(w)) of at least about 1×10⁶ g/mol, at least about 2×10⁶g/mol, or at least 5×10⁶ g/mol. The colloidal particles of drag reducingpolymer can have a mean particle size of less than about 10 microns,less than about 1,000 nm (1 micron), in the range of from about 10 toabout 500 nm, or in the range of from 50 to 250 nm. At least about 95percent by weight of the colloidal particles can be larger than about 10nm and smaller than about 500 nm. At least about 95 percent by weight ofthe particles can be larger than about 25 nm and smaller than about 250nm. The continuous phase can have a pH in the range of from about 4 toabout 10, or in the range of from about 6 to about 8, and contains fewif any multi-valent cations.

In one embodiment of the present invention, the drag reducing polymercan comprise at least about 10,000, at least about 25,000, or at least50,000 repeating units selected from the residues of the above mentionedmonomers. In one embodiment, the drag reducing polymer can comprise lessthan 1 branched unit per each monomer residue repeating unit.Additionally, the drag reducing polymer can comprise less than 1 linkinggroup per each monomer residue repeating unit. Furthermore, the dragreducing polymer can exhibit little or no branching or crosslinking.Also, the drag reducing polymer can comprise perfluoroalkyl groups in anamount in the range of from about 0 to about 1 percent based on thetotal number of monomer residue repeating units in the drag reducingpolymer.

As mentioned above, a liquid hydrocarbon can be treated with the dragreducing polymer in order to reduce drag associated with flowing theliquid hydrocarbon through a conduit. In order for the drag reducingpolymer to function as a drag reducer, the polymer should dissolve or besubstantially solvated in the liquid hydrocarbon. Accordingly, in oneembodiment of the present invention, the drag reducing polymer can havea solubility parameter that is within about 20 percent, about 18percent, about 15 percent, or 10 percent of the solubility parameter ofthe liquid hydrocarbon, as discussed above.

The solubility parameter of the drag reducing polymer is determinedaccording to the Van Krevelen method of the Hansen solubilityparameters. This method of determining solubility parameters can befound on pages 677 and 683-686 of Brandrup et al., Polymer Handbook(4^(th) ed., vol. 2. Wiley-Interscience, 1999), which is incorporatedherein by reference. According to Brandrup et al., the following generalequation was developed by Hansen and Skaarup to account for dispersiveforces, polar interactions, permanent dipole-dipole interactions, andhydrogen bonding forces in determining solubility parameters:

δ=(δ_(d) ²+δ_(p) ²+δ_(h) ²)^(1/2)

where δ is the solubility parameter, δ_(d) is the term adjusting fordispersive forces. δ_(p) is the term adjusting for polar interactions,and δ_(h) is the term adjusting for hydrogen bonding and permanentdipole-induced dipole. Systems have been developed to estimate the aboveterms using a group contribution method, measuring the contribution tothe overall solubility parameter by the various groups comprising thepolymer. The following equations are used in determining the solubilityparameter of a polymer according to the Van Krevelen method:

δ_(p)=(ΣF² _(pi))^(1/2)/V

δ_(h)=(ΣE_(hi))^(1/2)

δ_(d)=(ΣF_(dt)/V

The above equations and an explanation of how they are used can be foundon pages 677 and 683-686 of Brandrup et al. The values for the variablesF and E in the above equations are given in table 4, page 686 ofBrandrup et al., based on the different residues comprising a polymer.For example, a methyl group (—CH₃) is given the following values: F=420(J^(1/2)cm^(3/2)/mol), F_(pi)=0 (J^(1/2)cm^(3/2)/mol), E_(hi)=0 J/mol.Additionally, the values for the variable V in the above equations aregiven in Table 3 on page 685 where, for example, a methyl group (—CH₃)is given a value of V=33.5 (cm³/mol). Using these values, the solubilityparameter of a polymer can be calculated.

In one embodiment of the present invention, the drag reducing polymercan have a solubility parameter, as determined according to the aboveequations, of at least about 17 MPa^(1/2), in the range of from about17.1 to about 24 MPa^(1/2), or in the range of from 17.5 to 23MPa^(1/2). Furthermore, the drag reducing polymer can have a solubilityparameter that is within about 4 MPa^(1/2), within about 3 MPa^(1/2), orwithin 2.5 MPa^(1/2) of the solubility parameter of the liquidhydrocarbon.

The drag reducing polymer can be added to the liquid hydrocarbon in anamount sufficient to yield a drag reducing polymer concentration in therange of from about 0.1 to about 500 ppmw, in the range of from about0.5 to about 200 ppmw, in the range of from about 1 to about 100 ppmw,or in the range of from 2 to 50 ppmw. In one embodiment, at least about50 weight percent, at least about 75 weight percent, or at least 95weight percent of the solid drag reducing polymer particles can bedissolved by the liquid hydrocarbon. In another embodiment, theviscosity of the liquid hydrocarbon treated with the drag reducingpolymer is not less than the viscosity of the liquid hydrocarbon priorto treatment with the drag reducing polymer.

The efficacy of the high molecular weight polymer particles as dragreducers when added directly to a liquid hydrocarbon is largelydependent upon the temperature of the liquid hydrocarbon. For example,at lower temperatures, the polymer dissolves at a lower rate in theliquid hydrocarbon, therefore, less drag reduction can be achieved.Thus, in one embodiment of the present invention, the liquid hydrocarboncan have a temperature at the time of treatment with the drag reducingpolymer of at least about 30° C., or at least 40° C.

The drag reducers employed in the present invention can providesignificant percent drag reduction. For example, the drag reducers canprovide at least about 5 percent drag reduction, at least about 15percent drag reduction, or at least 20 percent drag reduction. Percentdrag reduction and the manner in which it is calculated are more fullydescribed in Example 5, below.

EXAMPLES

The following examples are intended to be illustrative of the presentinvention in order to teach one of ordinary skill in the art to make anduse the invention and are not intended to limit the scope of theinvention in any way.

Example 1: Preparation of Polymer A and Polymer B

In this example, two formulations for the materials used in laterexamples are detailed. The resulting material in each procedure is adispersion of drag reducing polymer in an aqueous carrier.

Preparation of Polymer A

Polymerization was performed in a 185-gallon stainless steel, jacketedreactor with a mechanical stirrer, thermocouple, feed ports, andnitrogen inlets/outlets. The reactor was charged with 440 lbs of monomer(2-ethylhexyl methacrylate), 558.1 lbs of dc-ionized water, 41.4 lbs ofPolystep B-5 (surfactant, available from Stepan Company of Northfield,Illinois), 44 lbs of Tergitol 15-S-7 (surfactant, available from DowChemical Company of Midland, Mich.), 1.86 lbs of potassium phosphatemonobasic (pH buffer), 1.46 lbs of potassium phosphate dibasic (pHbuffer), and 33.2 grams of ammonium persulfate, (NH₄)₂S₂O₈ (oxidizer).

The mixture was agitated at 110 rpm to emulsify the monomer in the waterand surfactant carrier. The mixture was then purged with nitrogen toremove any traces of oxygen in the reactor and cooled to about 41° F.The agitation was slowed down to 80 rpm and the polymerization reactionwas initiated by adding into the reactor 4.02 grams of ammonium iron(II)sulfate, Fe(NHe)₂(SO₄)₂.6H₂O in a solution of 0.010 M sulfuric acidsolution in DI water at a concentration of 558.3 ppm at a rate of 10g/min. The solution was injected for 10 hours to complete thepolymerization. The resulting latex was pressured out of the reactorthrough a 5-micron bag filter and stored. The solubility parameter ofPolymer A was calculated to be 18.04 MPa^(1/2).

Preparation of Polymer B

Preparation of Polymer B was performed in the same manner as thepreparation of Polymer A above, with the following exception: themonomer charged to the reactor was an 80/20 weight percent blend of2-ethylhexyl methacrylate and n-butyl acrylate. The solubility parameterof Polymer B was calculated to be 20.55 MPa^(1/2).

Example 2: LP 100 and LP 300

LP 100 FLOW IMPROVER (LP 100) and LP 300 FLOW IMPROVER. (LP 300)underwent various tests described below and were compared to theexperimental drag reducers of the present invention, Polymer A andPolymer B, as described in Example 1. LP 100 and LP 300 are dragreducing agents comprising polyalphaolefins. Specifically, LP 100comprises poly(1-decene) and LP 300 comprises a copolymer ofpoly(l-decene) and poly(l-tetradecene). Both LP 100 and LP 300 arecommercially available from ConocoPhillips Specialty Products Inc. Thesolubility parameter of the polymer in LP 100 was calculated to be 16.49MPa^(1/2), and the solubility parameter of the polymer in LP 300 wascalculated to be 16.54 MPa^(1/2).

Example 3: Asphaltene Content and Elasticity Response (Affinity)

Crude oils ranging in classification from heavy crudes to light crudeswere first tested to determine their respective concentrations ofasphaltene and their API gravities. These same crude oil samples werealso tested to determine their affinity for drag reducing agents asprepared in Examples 1 and 2. The results are listed in Table 1 below.

Asphaltene concentration was determined using pentane precipitation andfiltration. For each measurement listed in Table 1, a 40-fold volume ofpentane was added to approximately 16 grams of crude oil sample. Themixtures were agitated via rolling for an overnight period, and allowedto set for approximately 24 hours. The mixtures were then filteredthrough a 0.8 micrometer filter to retain the asphaltene. Theasphaltenes retained were then weighed, and the weight percent wascalculated based upon the original crude oil sample weight. API gravitywas determined in accord with ASTM test method D1298.

The crude oil's affinity for drag reducing agents was determined byassessing each crude oil's elasticity after being treated with a dragreducing agent. Four samples of each variety of crude oil were dosed atroom temperature with 5 weight percent of Polymer A, Polymer B, LP 100,and LP 300 respectively. The samples were allowed to roll overnight toinsure full dissolution of the drag reducing agent into the samples.After rolling, the samples were visually inspected for their elasticresponse by inserting a hooked-end spatula into the sample and pullingthe spatula away from the bulk of the sample. Some samples yielded ahigh response, meaning that a highly elastic “string” or “rope” of crudeoil could be pulled from the sample. Conversely, some samples yielded noresponse, meaning that the crude oil merely dripped from the spatula.

TABLE 1 Asphaltene Content, API Gravity, and Elasticity ResponseASPHALTENE ELASTICITY RESPONSE CONTENT (AFFINITY) Crude Oil Test TestAPI LP LP Polymer Polymer Sample Type 1 2 Gravity 100 300 A B MereyHeavy 16.8 15.5 16.0° None None High High Petrozuata Heavy 18.8 18.19.1° None None High High Corocoro Heavy 6.0 6.7 25.1° None None HighHigh Albian Heavy 11.0 10.6 22.4° None None High High Bow River Heavy11.4 10.3 21.8° None None High High Maya Heavy 14.6 15.4 21.9° None NoneHigh High Western Heavy 11.5 11.9 20.9° None None High High CanadianSelect San Joaquin Heavy 8.9 8.9 13.0° None None High High Valley MarlimHeavy 6.7 6.6 22.2° High High High High Blend West Texas Intermediate2.8 2.8 31.6° High High Moderate Moderate Sour West Texas Light 0.5 —41.6° High High Moderate Moderate Intermediate Basrah Light 4.8 — 31.0°High High Moderate Moderate

The results in Table 1 tend to show that crude oils having a higherasphaltene content and/or lower API gravity have a higher affinity forPolymers A and B than for LP 100 and 300. Evidence of stronger affinity(i.e., increased elasticity) is generally an indication of a higherpotential for performance as a drag reducing agent.

Example 4: Extensional Rheometry

The extensional viscosity (or extensional behavior) of a fluid treatedwith a drag reducing polymer is directly related to the polymer'spotential for reducing turbulent drag in the fluid. If increasedextensional behavior is observed in the fluid upon addition of the dragreducing polymer, this is indicative of increased potential for dragreduction performance. Conversely, if no extensional behavior isobserved, the potential for drag reduction performance in that fluid isunlikely. The extensional behavior of a treated fluid can be determinedby capillary breakup extensional rheometry testing, performed on a HAAKECaBER 1, available from Thermo Electron Corp., Newington, N.H., U.S.A.

The HAAKE CaBER 1 is operated by placing a small quantity of sample(less than 0.1 ml) between top and bottom circular plates using a 16gauge, i-inch long syringe needle. The top plate is rapidly separatedupwardly from the bottom plate at a user-selected strain rate, therebyforming an unstable fluid filament by imposing an instantaneous level ofextensional strain on the fluid sample. After cessation of stretching,the fluid at the mid-point of the filament undergoes an extensionalstrain rate defined by the extensional properties of the fluid. A lasermicrometer monitors the midpoint diameter of the gradually thinningfluid filament as a function of time. The competing effects of surfacetension, viscosity, mass transfer and elasticity can be quantified usingmodel fitting analysis software.

In this example, three samples were prepared and tested for extensionalrheometry using a HAAKE CaBER 1. The first sample was untreated (neat)San Juaquin Valley Heavy (SJVH) crude oil. The second sample was SJVHcrude containing 500 ppmw of the active polymer found in Polymer A(poly(2-ethylhexyl methacrylate)) as prepared in Example 1, and thethird sample was SJVH crude containing 500 ppmw of the active polymerfound in LP 100 (poly(1-decene)) as described in example 2. According tothe procedure described above, less than 0.1 ml of each of these threesamples was placed between the two plates of the CaBER 1, and the plateswere separated quickly while measuring the diameter of the resultantfilament. For each test, the default instrument settings were employed,and a Hencky strain of c=0.70 was used. Hencky strain is defined as:

$ɛ = {{\ln\left( \frac{L}{L_{0}} \right)}\mspace{14mu} {where}\mspace{14mu} \frac{L}{L_{0}}}$

is the relative extension of the fluid. The diameter of the resultantfilament was measured against time. Each sample in the above describedprocedure was tested 10 times to obtain statistical confidence in thedata. The results from these tests are shown in FIGS. 1 through 3.Additionally, each test was performed at a room temperature of about 25°C.

In each of FIGS. 1, 2, and 3, the filament diameter was normalized, suchthat a filament diameter of d/d₀ is shown, where d₀ is the filamentdiameter at time zero (0 seconds) and d is the filament diameter at anygiven time thereafter. The results from these tests show that theextensional behavior of the untreated SJVH crude oil and SJVH crude oilcontaining 500 ppmw the active polymer found in LP 100 (poly(l-decene))are very similar (shown in FIGS. 1 and 3, respectively), indicating thatLP 100 does not have any noticeable potential for reducing drag of heavycrude oil in a pipeline. However, SJVH having 500 ppmw of the activepolymer found in Polymer A (poly(2-ethylhexyl methacrylate)) shows asignificant increase in extensional rheometry, as shown in FIG. 2. Thisincrease in extensional rheometry indicates an increased potential forPolymer A to reduce drag of heavy crude oil in a pipeline.

Example 5: Pipeline Testing

Pipeline field testing was performed with various diameter pipelines,and various crude oils, comparing the performance of Polymers A and B,as prepared in Example 1, with LP 100 and LP 300, as described inExample 2. The following three tests were performed, followed by theirrespective results in tables 2, 3, and 4. For each of the three testsdescribed below, the percent drag reduction (% DR) was determined bymeasuring the pressure drop in the segment of pipe being tested prior toaddition of drag reducing agent (ΔP_(base)) and measuring the pressuredrop in the segment of pipe being tested after addition of drag reducingagent (ΔP_(treated)). The percent drag reduction was then determinedaccording to the following formula:

% DR=((ΔP_(base)−ΔP_(treated))/ΔP_(base))×100%

Test 1

Test 1 was conducted in a 12-inch diameter crude oil pipeline carryingWest Texas Intermediate (WTI) crude oil. This crude oil is a lightcrude, generally having an API gravity of about 400. WTI generally has aviscosity of approximately 4.5 centistokes at pipeline temperatures of65 to 69° F. The pipeline tests in Test 1 were conducted in a 62-milesegment of the pipeline running from Wichita Falls, Tx., to Bray, Okla.The nominal flow rate of the pipeline during the field tests was 2,350barrels/hr, and the nominal flow velocity in the pipeline was 4.5 ft/s.The following drag reduction performance was achieved:

TABLE 2 LP 100 v. Polymer A & Polymer B in Light Crude (WTI)CONCENTRATION DRAG REDUCTION PRODUCT (ppmw) (%) LP 100 4.7 33.8 LP 10023.5 67.2 Polymer A 40.4 24.4 Polymer A 80.1 36.3 Polymer B 40.2 31.3Polymer B 81.0 40.4 Polymer B 150.4 45.7

Test 2

Test 2 was conducted in an 18-inch diameter crude oil pipeline carryingAlbian Heavy Sour (AHS) crude oil blend. This crude oil blend is a heavycrude oil, generally having an API gravity of about 22°. AHS generallyhas a viscosity of approximately 84 centistokes at a pipelinetemperature of 71° F. The pipeline tests in Test 2 were conducted in a54-mile segment of the pipeline running from Cushing, Okla., to Marland,Okla. The nominal flow velocity in the pipeline was 4.8 f/s. The nominalcalculated Reynolds number for the pipeline was 7,500. The followingdrag reduction performance was achieved:

TABLE 3 LP 100 v. Polymer B in Heavy Grade (AHS) CONCENTRATION DRAGREDUCTION PRODUCT (ppmw) (%) LP 100 41.6 0 Polymer B 35.2 23.1 Polymer B100.0 42.5

Test 3

Test 3 was conducted in an 8-inch diameter crude oil pipeline carryingSan Joaquin Valley Heavy (SJVH) crude oil blend. This crude oil blend isa heavy crude oil, generally having an API gravity of about 13°. SJVHgenerally has a viscosity of approximately 100 centistokes at a pipelinetemperature of 165° F. The pipeline tests in Test 3 were conducted in a14-mile segment of the pipeline running from the Middlewater pumpstation to the Junction pump station, both in California. The nominalflow rate of the pipeline during Test 3 was 1,300 barrels/hr, and thenominal flow velocity in the pipeline was 5.6 ft/s. The nominalcalculated Reynolds number for the pipeline was 4,000. The followingdrag reduction performance was achieved:

TABLE 4 LP 300 v. Polymer A & Polymer B in Heavy Crude (SJVH)CONCENTRATION DRAG REDUCTION PRODUCT (ppmw) (%) LP 300 187.0 0 Polymer A50.0 28.5 Polymer A 100.0 39.5 Polymer B 50.0 28.8 Polymer B 100 36.7

Comparing the above three tests, the results listed in Table 2 tend toshow that the drag reduction achieved by addition of LP 100 product inlight crude oil yields slightly more favorable results than either ofthe EXP products. However, when heavy crude oils are used, as shown inTables 3 and 4, the use of Polymers A or B results in higher percentagesof drag reduction than either of the LP products.

Example 7: Alkyl Acrylates

The following monomers were emulsion polymerized and tested for theirdrag reducing properties:

% Drag Re- duction in Diesel WCS WTI Alkyl Carbon Alkyl Inherent at OilOil Acrylate Number Chain Viscosity 2 ppm Affinity Affinity n-Butyl 4Straight 14.2 0 0 0 Acrylate tert-Butyl 4 Branched 18.5 0 1.0 0 Acrylate2-ethyl- 8 Branched 11.5 12.9 4.5 1.5 hexyl Acrylate

As it is shown in the above mentioned example acrylates with alkylchains larger than 4 provided the greatest amount of drag reduction.

Example 8: Alkyl Methacrylates

The following polymers were emulsion polymerized and tested for theirdrag reducing proerties:

% Drag Re- duction in Alkyl Diesel WCS WTI Metha- Carbon Alkyl Inherentat Oil Oil crylate Number Chain Viscosity 2 ppm Affinity Affinity Methyl1 Straight 14.4 0 0 0 Metha- crylate n-Butyl 4 Straight 12.7 0 1.0 0Metha- crylate iso-Butyl 4 Branched 18.7 0 1.0 0 Metha- crylate Hexyl 6Straight 19.5 31.9 6.5 2.0 Metha- crylate 2-Ethyl- 8 Branched 18.6 36.87.0 1.5 hexyl Metha- crylate Isodecyl 10 Branched 14.3 24.8 9.5 2.0Metha- crylate Lauryl 12 Straight 12.6 17.2 9.0 3.0 Metha- crylate

As it is shown in the above mentioned example acrylates with alkylchains larger than 4 provided the greatest amount of drag reduction.

Numerical Ranges

The present description uses numerical ranges to quantify certainparameters relating to the invention. It should be understood that whennumerical ranges are provided, such ranges are to be construed asproviding literal support for claim limitations that only recite thelower value of the range as well as claims limitation that only recitethe upper value of the range. For example, a disclosed numerical rangeof 10 to 100 provides literal support for a claim reciting “greater than10” (with no upper bounds) and a claim reciting “less than 100” (with nolower bounds).

The present description uses specific numerical values to quantifycertain parameters relating to the invention, where the specificnumerical values are not expressly part of a numerical range. It shouldbe understood that each specific numerical value provided herein is tobe construed as providing literal support for a broad, intermediate, andnarrow range. The broad range associated with each specific numericalvalue is the numerical value plus and minus 60 percent of the numericalvalue, rounded to two significant digits. The intermediate rangeassociated with each specific numerical value is the numerical valueplus and minus 30 percent of the numerical value, rounded to twosignificant digits. The narrow range associated with each specificnumerical value is the numerical value plus and minus 15 percent of thenumerical value, rounded to two significant digits. For example, if thespecification describes a specific temperature of 62° F., such adescription provides literal support for a broad numerical range of 25°F. to 99° F. (62° F.+/−37° F.), an intermediate numerical range of 43°F. to 81° F. (62° F.+/−19° F.), and a narrow numerical range of 53′F to71° F. (62° F.+/−9° F.). These broad, intermediate, and narrow numericalranges should be applied not only to the specific values, but shouldalso be applied to differences between these specific values. Thus, ifthe specification describes a first pressure of 110 psia and a secondpressure of 48 psia (a difference of 62 psi), the broad, intermediate,and narrow ranges for the pressure difference between these two streamswould be 25 to 99 psi, 43 to 81 psi, and 53 to 71 psi, respectively.

Definitions

As used herein, the terms “comprising,” “comprises,” and “comprise” areopen-ended transition terms used to transition from a subject recitedbefore the term to one or more elements recited after the term, wherethe element or elements listed after the transition term are notnecessarily the only elements that make up the subject.

As used herein, the terms “including,” “includes,” and “include” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “having,” “has,” and “have” have the sameopen-ended meaning as “comprising,” “comprises.” and “comprise.”

As used herein, the terms “containing,” “contains,” and “contain” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “a,” “an.” “the,” and “said” mean one or more.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itselfor any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

The preferred forms of the invention described above are to be used asillustration only, and should not be used in a limiting sense tointerpret the scope of the present invention. Obvious modifications tothe exemplary embodiments, set forth above, could be readily made bythose skilled in the art without departing from the spirit of thepresent invention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of thepresent invention as pertains to any apparatus not materially departingfrom but outside the literal scope of the invention as set forth in thefollowing claims.

What is claimed is:
 1. A process, comprising: a) obtaining a first batchof monomers selected from the group consisting of acrylates with amolecular weight equal to or less than butyl acrylate, methacrylateswith a molecular weight equal to or less than butyl methacrylate andcombinations thereof; b) obtaining a second batch of monomers selectedfrom the group consisting of acrylates with a molecular weight greaterthan butyl acrylate, methacrylates with a molecular weight greater thanbutyl methacrylate and combinations thereof; c) preparing a mixturecomprising the first batch of monomers and the second batch of monomerswherein the second batch is greater than 50% by weight of the mixture;and d) processing the mixture to produce a drag reducing polymer capableof imparting drag reducing properties in liquid hydrocarbons.
 2. Theprocess of claim 1, wherein the drag reducing polymer is introduced intoa pipeline, such that the friction loss associated with the turbulentflow through the pipeline is reduced by suppressing the growth ofturbulent eddies.
 3. The process of claim 1, wherein the drag reducingpolymer is added to the liquid hydrocarbon in the range from about 0.1to about 500 ppmw.
 4. The process of claim 2, wherein the drag reducingpolymer contacts a liquid hydrocarbon in the pipeline to produce atreated liquid hydrocarbon wherein the viscosity of the treated liquidhydrocarbon is not less than the viscosity of the liquid hydrocarbonprior to treatment with the drag reducing polymer.
 5. The process ofclaim 1, wherein the drag reducing polymer has a solubility parameterwithin 4 MPa^(1/2) of the solubility parameter of the liquidhydrocarbon.
 6. A process, comprising: a) obtaining a first batch ofmonomers selected from the group consisting of acrylates with side alkylchains having four or less carbons, methacrylates with side alkyl chainshaving four or less carbons and combinations thereof; b) obtaining asecond batch of monomers selected from the group consisting of acrylateswith side alkyl chains having greater than four carbons, methacrylateswith side alkyl chains having greater than four carbons and combinationsthereof; c) preparing a mixture comprising the first batch of monomersand the second batch of monomers wherein the second batch is greaterthan 50% by weight of the mixture; and d) polymerizing the mixture toproduce an ultra high molecular weight polymer wherein the drag reducingpolymer is capable of imparting drag reducing properties in liquidhydrocarbons.
 7. A process of claim 6, wherein monomers of the secondbatch of monomers have branched side alkyl chains.
 8. The process ofclaim 6, wherein the drag reducing polymer is introduced into apipeline, such that the friction loss associated with the turbulent flowthrough the pipeline is reduced by suppressing the growth of turbulenteddies.
 9. The process of claim 8, wherein the drag reducing polymercontacts a liquid hydrocarbon in the pipeline to produce a treatedliquid hydrocarbon wherein the viscosity of the treated liquidhydrocarbon is not less than the viscosity of the liquid hydrocarbonprior to treatment with the drag reducing polymer.
 10. The process ofclaim 6, wherein the drag reducing polymer has a solubility parameterwithin 4 MPa^(1/2) of the solubility parameter of the liquidhydrocarbon.
 11. The process of claim 6, wherein the drag reducingpolymer is added to the liquid hydrocarbon in the range from about 0.1to about 500 ppmw.